# coding:utf-8

from datetime import datetime
from datetime import timedelta
now = datetime.now()
print(now,type(now))
now_str =now.strftime('%y-%m-%d %H:%M:%S')
print(now_str,type(now_str))
print('-------------------------')

now_obj = datetime.strptime(now_str, '%y-%m-%d %H:%M:%S')
print(now_obj)

print('-------------------------------')

three_days = timedelta(days=3)
after3 = now + three_days
print(after3)
stry_after3 = after3.strftime('%y/%m----------------%d %H:%M:%S:')
print(stry_after3)
befor3 = now - three_days
print(befor3)

​错误代码：

D:\pythonwork\venv\Scripts\python.exe D:/pythonwork/python_package/package_datetime.py

2021-06-30 13:48:29.874789 <class 'datetime.datetime'>

21-06-30 13:48:29 <class 'str'>

-------------------------

Traceback (most recent call last):

  File "D:/pythonwork/python_package/package_datetime.py", line 11, in <module>

    now_obj = datetime.strptime(now_str, '%y-%m-%d %H:%M:%S')

  File "C:\Users\tianyu\AppData\Local\Programs\Python\Python37\lib\_strptime.py", line 14, in <module>

    import locale

  File "C:\Users\tianyu\AppData\Local\Programs\Python\Python37\lib\locale.py", line 16, in <module>

    import re

  File "C:\Users\tianyu\AppData\Local\Programs\Python\Python37\lib\re.py", line 125, in <module>

    import functools

  File "C:\Users\tianyu\AppData\Local\Programs\Python\Python37\lib\functools.py", line 21, in <module>

    from collections import namedtuple

  File "C:\Users\tianyu\AppData\Local\Programs\Python\Python37\lib\collections\__init__.py", line 22, in <module>

    from keyword import iskeyword as _iskeyword

ImportError: cannot import name 'iskeyword' from 'keyword' (D:\pythonwork\keyword.py)

Process finished with exit code 1